Mia Farrow blames elective heart surgery for the death of her mother, actress Maureen O'Sullivan.

"She was in full sail; in the bloom of her life," Farrow said in a column by Liz Smith on Monday. "She went in for elective surgery on her carotid arteries and after the first successful operation, she had the second operation three days later. That caused her to die of heart failure."When O'Sullivan, 87, died on June 22 in Arizona, her family did not elaborate on the cause of her death.